Movable winches are often used in an industrial environment for moving light or heavy equipment from place to place. The apparatus used for moving and/or locking the winch into place is often both bulky and difficult to maneuver as it relies primarily upon its own weight to anchor the winch for use in hauling equipment toward the winch. Alternatively, it may be necessary to bolt the winch securely in place, which requires time and effort.
The use of a controllable vacuum chamber for purposes of anchoring the winch is attractive here, as it allows the use of much smaller machinery for moving and/or holding the winch stationary. The negative pressure of downward-directed atmospheric force developed by a hemispherical vacuum chamber of one foot radius can approach 6700 pounds. A releasable vacuum cup, used for securing a chair to a deck or floor, is disclosed in U.S. Pat. No. 961,093 to Astor, where the top of the vacuum cup is raised and/or depressed by of a rack and pinion to create a partial vacuum within the cup. Evidently, the cup material must be elastic or pliant.
U.S. Pat. No. 2,101,399 to Larsen teaches the use of vacuum cups, again of pliant material, on the landing surfaces of a helicopter or similar vertical descent aircraft so as to restrict vertical or horizontal motion of the aircraft after landing. Each vacuum cup is provided with a valve and a ball and socket mechanism so that the cup may accomodate itself to tilting movement of the aircraft and/or to terrain irregularities. A minimum of three vacuum cups is evidently needed for operation of the invention.
U.S. Pat. No. 2,123,549 to Williams discloses and claims a vacuum cup with a series of concentric layers of ridges or sealing lips, to prevent entrance of moisture and/or loss of vacuum; the entire cup being pliant and self-contouring so as to be useful in holding a tray, for example, on a rounded part of an automobile body. The vacuum pump and valve means are activated by other devices.
Heiden, In U.S. Pat. No. 2,945,242, discloses the use of one or more vacuum cups, activated by a downward force through a mechanical linkage, to make contact with the ground and immobilize the associated structure (wheelchair, rollable table, etc.). Apparently, the novelty in Heiden resides in the use of tubes within the associated structure to bleed the vacuum from the cups.
In U.S. Pat. No. 3,159,370, Rubinstein teaches and claims a vacuum chamber including a rigid convex (hollow) housing open on the bottom; a rubber pad, stretched across the mouth of the housing, a rigid flat surface, being rigidly attached to the central portion of the pad with a shape generally conforming to the interior of the housing; and a crank which causes the pad to move upward against the housing or downward against a flat surface against which the mouth of the housing is pressed so as to create or release a vacuum within the housing, which holds the housing to the surface.
Of the abovementioned patents, only the patent of Rubinstein uses a rigid (non-pliant) vacuum cup, and none of these patents teaches the use of a housing of sufficient size to develop a total immobilization force of several thousand pounds (negative pressure).